Motorola Mototrbo - 2.0 Troubleshooting Flow Chart for 40 W Transmitter

1-4 Troubleshooting Flow Chart for 40W Transmitter
2.0 Troubleshooting Flow Chart for 40W Transmitter
No or Low
Transmitter Power
Is TP0710
>1 VDC?
Is U3002 Pin 1
= 9.1 VDC?
Is U3002 Pin 5
= 5 VDC?
Is voltage at
Tx_DAC input
(U0904 Pin 1)
> 3 VDC?
Is voltage at
U0902 Pin 3
> 3 VDC?
Is voltage at
TP0900
> 1 VDC?
Is power at
D0877-A
~47dBm?
Verify that voltage on C0758
and C0759 is ~13.2 VDC.
Replace Q0705 if necessary.
Verify that Q0704 Vgs (at
R0719) is ~2.2 VDC and Vds
(TP0705) ~9.3 VDC. Replace
Q0704 if necessary.
Verify that Q0700 Vgs
(TP0700) is ~2.4 VDC and
Vds (TP0702) ~9.3 VDC.
Replace Q0700 if necessary.
Is power at
TP0705
~37dBm?
Is power at
TP0702
~27dBm?
Is power at
TP0704
~12dBm?
Is power at
TP0703
~-4dBm?
Check RFIC
Replace Q0703
Check VCO
Troubleshooting
Flowchart
Is R0739 ~3-4
VDC?
Are TP0706 and
TP0707 ~2.2
VDC?
Measure relative power thru remainder of T/R
switch and low-pass filter (LPF) to find open
circuit. Perform visual inspection of circuit.
Replace U0904
Replace U0902
Replace U0901
Check 9.3V Regulator in
Power Management
Replace U3002
Check RFIC
Is TP0705
= 9.3 VDC?
Is D0875-A
~0.8 VDC?
Check DC voltage on
Q3001 pin 2, R3019,
D3000, R3015 in 9V3_PA
Regulator in Controller
Troubleshooting Flowchart.
Replace any component
that does not have 9.3 VDC
across it.
Replace D0875. Also check if
D0877-A is ~1.6 VDC (to
GND). Replace D0877 if
necessary.
Check RD70 bias circuitry
components (R0738, R0740, R0742,
R0744, R0737, C0753, C0754, R0741,
R0743, C0761, C0764 and R0746) for
shorts, opens or bad solder joints.
Replace components as needed.
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